3-Phase Motor Amperage Calculator

Written by Great Medico

Updated September 25, 2026 •2 min read

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Short physics utilities are most useful when units and assumptions stay visible. 3-Phase Motor Amperage Calculator focuses on three-phase motor current from the fields on this page, while the notes below separate the governing relation from real-world design, measurement, and safety constraints.

What this calculator does

The 3-Phase Motor Amperage Calculator brings together Load distribution, Voltage type, Motor voltage (V), Motor power rating (P), Power factor (cos Φ) around the page’s three-phase motor current. The formula section below identifies which values actually drive that result and which fields are supporting or derived quantities, so you can check the page without assuming every visible box is an independent input.

How to use it

The main fields on this page are Load distribution, Voltage type, Motor voltage (V), Motor power rating (P), Power factor (cos Φ). Enter the quantities you actually know, keep their units consistent, and leave derived/output-style fields blank unless the formula explicitly allows solving in the opposite direction. For a clean check of three-phase motor current, change one driving quantity at a time and confirm that the result moves in the direction predicted by the equation.

How the calculation works

The active legacy relation is I = P/(√3·V·PF·η), with the handler treating the numeric power input as kilowatts before multiplying by 1000. It estimates balanced three-phase line current from power, voltage, power factor, and efficiency.

Example

For example, start with the page’s populated scenario: Load distribution = balanced; Voltage type = line. Apply the equation above using the units shown on the page, then compare the calculated three-phase motor current with the displayed result. As a second check, change one physical input while holding the others fixed and confirm that the direction of change makes sense for this formula.

How to interpret the result

Interpret three-phase motor current as the output of the stated physics relation. Check units, signs, and the direction of change against the equation; when the result feeds a real design or measurement, apply the additional constraints that the page does not model.

Limitations and notes

The active handler multiplies the numeric power input by 1000, so its intended power basis is kW. If the page unit selector is set to W without a matching conversion before this handler, current can be off by a factor of 1000. Always verify I = P/(√3VPFη) in consistent units.